Speed reducing or increasing planetary gear apparatus

A planetary gear apparatus including:

• an external gear mounted on an input shaft with an eccentric member and a bearing fitted onto said eccentric member therebetween;
• an internal gear engaging with said external gear, said internal gear being coaxial with respect to said input shaft;
• an output shaft for outputting a reduced rotational force;
• and a drive for coupling said external gear and said output shaft, said planetary gear apparatus being adapted to transmit the rotational force of said input shaft to said output shaft after it has reduced the speed of said rotational force, or to transmit the rotational force of said output shaft to said input shaft after it has increased the speed of said rotational force, by fixing the internal gear,
• characterized in that said external gear has a ring-like shape, that the inner peripheral surface of said external gear is provided with a hole into which said bearing that is fitted onto said eccentric member is fitted, that splines are formed on said insertion hole over the entire axial length of the external gear in such a manner that they are coaxial with respect to said external gear, that said bearing is fitted into one end side of said bearing insertion hole, said bearing having a width shorter than that of each of said splines, that said drive having an end provided with splines is engaged with the other end side of said bearing insertion hole, that the other end of said drive is provided with splines or spline grooves, and that said splines or said spline grooves are engaged with spline grooves or splines provided in said output shaft.